A typical logging truck has a series of bunks arranged across a bed of the truck for supporting logs during a hauling operation. Each bunk has a pair of laterally spaced apart and vertically extending stakes, between which logs are stacked. During a loading operation, logs are typically loaded onto the bunks by an operator using a grapple on the end of a boom loader. A skilled operator using a boom loader is capable of precisely and efficiently manipulating logs to deposit them across adjacent pairs of bunks. In this manner, loaded logs are captured along each bunk, between an associated pair of stakes. For self-loading trucks having an integral loading bed, a boom loader is often mounted directly onto the truck to enable self loading between the stakes. Alternatively, for logging trailers, the logs are typically loaded onto the trailer with another vehicle having a boom loader.
To enable complete loading of a trailer carrying logs having a relatively low density or having a relatively small diameter, extendible stakes are used to increase the volumetric carrying capacity of a trailer. For cases where large diameter loads, or high density logs are carried, the extendible stakes can be used in their lowered, or conventional-height configuration. Whereas, for situations where the load limits of the truck and trailer have not been reached, the height of the load area can be increased by extending the bunk stakes.
In some cases, bunk stakes are made adjustable in height in order to reduce clearance requirements of a truck and trailer when empty or partially loaded. If tall bunk stakes are immovably mounted atop a trailer, access to certain logging sites might be restricted due to clearance conditions under bridges and signs. Similarly, storage of such a trailer within a garage or building might be hindered. Furthermore, for tractor-trailer devices having a removable trailer portion that loads atop the tractor for a return trip home, it is necessary that bunk stakes be retractable in order to provide necessary road clearance. Such tractor-trailer combinations typically have one bunk on the tractor and another bunk on the trailer. When the trailer is loaded atop the tractor, the trailer bunk stake is raised to an even higher elevation. Therefore, there is an even greater need to have a retractable bunk stake on such a tractor-trailer combination.
One technique that enables an operator to extend the height of a bunk stake consists of manually raising and lowering a movable extension member carried within a tubular support member of a stake. However, a truck operator must climb on top of the trailer bunk in order to raise and lower the extension. While on the bunk, the operator is exposed to potential injury, particularly during loading operations. Additionally, the operator is susceptible of falling from the bunk during raising and lowering of the extension, particularly during inclement weather conditions.
Another technique for raising a bunk stake extension involves manipulation of the extension member with a log in order to raise it to a vertically extended position. This technique is used with bunk stakes having a holding arm provided on top of the extension. The arm has a barb-shaped portion configured to engage a log as it is lifted vertically from below the arm by an operator using a grapple loader. A spring-loaded latch engages with the extension member to lock the extension member within the support member. In this manner, the extension member is locked in a vertically raised position. However, it proves to be awkward and difficult to raise a stake extension in this way. Additionally, a log must be raised by an operator in order to raise the extension which adds to the danger present from an operator dropping a log. Furthermore, a truck operator must still climb up onto the trailer to manually release the latch in order to lower the extension member.
Therefore, there is a need for an extendible bunk stake that can be easily and safely raised and lowered by a truck operator. Furthermore, there is a need for an extendible bunk stake that can be raised and lowered without requiring that a truck operator climb on top of a bunk, greatly reducing any risk of injury.